| 摘要 |
A ball screw actuator for a control surface of an aircraft includes a rotatable input shaft (16) which is driven, in use, by a drive shaft (22) and which is coupled to a non-rotatably mounted output shaft (10). The input shaft (16) has a screw thread formation including a groove within which a plurality of spherical members (20) are received to provide a ball screw coupling between the input shaft (16) and the output shaft (10). The drive shaft (22) is arranged to impart a drive load to the input shaft (16) through an intermediate drive arrangement (23) including a carrier member (28) and a shear pin (30) which is coupled to the carrier member (28) and arranged to shear across a shear gap in the event that the drive load applied by the drive shaft (22) exceeds a predetermined amount, thereby to break the coupling between the drive shaft (22) and the input shaft (16). The shear pin (30) is coupled to the carrier member (28) such that the shear gap remains substantially constant throughout the actuator service life. <IMAGE> |
